September 27,2011 

Via Electronic Transmittal: cozzie.david@epamail.epa.gov 

ward.hillary@epamail.epa.gov 

Ms. Hillary Ward 

Sector Policies and Programs Division (E143-01) 

Office of Air Quality, Planning and Standards 

U.S. Environmental Protection Agency 

109 T.W. Alexander Drive 

Research Triangle Park, NC 27709 

Dear Hillary: 

We appreciate your taking time on bgust 30, 20'1Uo discuss options with industry 

stakeholders for addressing wellhead operating standards pursuant to EPA's revisions of 40 CFR 

60 Subpart WWW (Landfill NSPS). As promised, we prepared recommendations for rule 

revisions and clarifications pursuant to current wellhead operating standards. 

When EPA established the wellhead standards for pressure, temperature and oxygen/nitrogen, 

many landfills did not have extensive experience with installing, operating and maintaining LFG 

collection and control systems (GCCS), or in operating beneficial landfill gas to energy projects. 

The industry also ~i~ not have any experience withr'lJmeric wellhead stand~!~~L,!nd~id not 

fully comprehend the implications. At the time, EPA was concerned about developing standards 

that would help ensure that GCCS were operated to prevent formation of landfill fires, prevent 

inhibition of anaerobic decomposition, and effectively control surface emissions. It has been 15 

years since the Landfill NSPS was promulgated, and in that time the landfill sector has gained a 

great deal of experience with GCCS and landfill gas to energy systems. In fact, the majority of 

landfills subject to the NSPS have installed GCCS systems, either because they have triggered 

the requirement to do so or have voluntarily installed gas collection systems early. 

Efforts to comply with the prescriptive Landfill NSPS wellhead standards in 60.753(c), 

particularly the oxygen/nitrogen and temperature limits can often be counterproductive to 

controlling surface emissions of methane. In order to control temperature and 

oxygen/nitrogen levels, landfill owner/operators must reduce the vacuum applied to the wells. 

This in turn reduces the gas collection efficiency of the system - a system designed to prevent 

surface emissions. For example, climate and waste characteristics often result in landfill gas 

temperatures routinely measured in excess of 55 degrees Centigrade (131 degrees Fahrenheit). 

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Additionally, arid landfills, non-producing landfill areas and interim early gas collection devices 

may routinely exhibit elevated oxygen levels. Although the NSPS allows landfill 

owner/operators to establish a higher operating value (HOV) with a demonstration that 

elevated parameter{s) do not cause fires or significantly inhibit anaerobic decomposition, many 

state agencies require an affirmative agency approval. Obtaining such approvals can take 

months or even years. In extreme cases, agencies deny or never respond to HOV requests 

leaving the facility in compliance limbo. Generally this occurs because they do not fully 

understand how GCCS operate. 

Industry Recommendation for Revisions to the NSPS based on Operational Experience 

Following are two recommendations for revisions to the NSPS that address wellhead operating 

standards and basis for our recommendations. 

1. Eliminate the pressure, temperature and oxygen/nitrogen standards in the NSPS: 

The prescriptive wellhead standards were included in the NSPS to guide landfill 

owners/operators in operating the new gas collection and control systems, specifically to 

prevent subsurface oxidation events. Since the rule promulgation in 1996, the industry has 

gained significant and widespread field operations experience. The existing wellhead standards 

are not the best indicator of GCCS performance because they are arbitrary limits on a limited 

number of parameters which do not accurately represent proper GCCS performance. This 

limited data does not provide a complete analysis of what is happening within the landfill in all 

situations. As a result, most landfill owner/operators monitor additional parameters (e.g., 

methane, carbon dioxide, balance gas, flow, and header pressure) to properly understand what 

is happening within the landfill and to optimize GCCS operations. There are so many variables it 

would be extremely difficult to develop regulatory standards that address all common 

operating scenarios. 

Further, the existing wellhead operating standards do not provide any additional protection to 

the environment because the landfill owner/operator is already heavily incentivized to 

maximize GCCS collection efficiency to control odor, control subsurface migration, minimize 

groundwater impacts, maintain cap stability and integrity, control surface emissions, and 

maximize energy recovery. In addition, landfill owners and operators diligently operate to 

avoid causing subsurface fires as potential damage to leachate containment liners, gas 

collection and control systems and other environmental controls can result in non-compliance 

and be extremely costly to mitigate. 

The temperature limit in NSPS was established as an alert level that may indicate a problem 

that prompts further investigation; well temperature at or above 55 degrees Celsius (0C) does 

not mean there is a fire or indicate improper operation. A well temperature at or above 55°C 

may be normal operating conditions for a facility based on site-specific climate and waste 

characterization. In the rulemaking record, EPA states that vacuum adjustment is the solution 

to reduce temperature, nofsystem expansion (see section 1.2.2.6 and response to comments 

Page 2-110). Nonetheless, some state agencies have required automatic system expansions as 

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an attempted resolution for higher temperature readings at wellheads because of current 

wording in the NSPS. 

With over 15 years of Gees operational experience, the prescriptive wellhead standards require 

extensive industry and agency resources to demonstrate and/or approve HOVs at sites where 

other data indicates no issues with respect to surface emissions, subsurface fires or improper 

Gees operation. In the most extreme cases, agencies have required system expansion and/or 

enforcement actions were taken where site conditions did not warrant such actions (no fires, 

normal operations for site conditions). 

A landfill owner or operator must have flexibility to demonstrate proper performance of the gas 

collection system during the early stage of gas collection (i.e., front end of the gas generation 

curve). It is often difficult to meet NSPS operational standards using interim control, such as a 

leachate collection system, since 1) they are not designed to be air tight; 2) they are not "in" 

refuse, but are instead below or adjacent to the refuse; and 3) piping that conveys leachate 

(and the landfill gas) may prevent the flow of landfill gas under all circumstances (e.g., when 

leachate sump levels are high). Large quantities of air often enter leachate collection systems 

because they are not designed to be air tight. However, this is not an issue because the air 

does not move through the waste and therefore will not cause subsurface oxidation within the 

refuse. Although the NSPS rules allow for alternative operational standards (Le., HOV for 

oxygen), regulatory agencies have been extremely reluctant to grant such alternatives due to 

unfamiliarity with LFG collection and control technology and existing site conditions. If EPA, as 

part of its revisions to the NSPS, plans to expedite timing of gas system installation, landfills will 

need more flexibility to address lower LFG quality and quantity and the ability to adapt system 

design and operations accordingly. Removal of the wellhead standards provides such 

operational flexibility. 

Just as a landfill owner or operator must have flexibility to demonstrate proper performance of 

the gas collection system during the early stage of gas collection similar flexibility is also needed 

to address declining flow situations (Le., back end of the gas generation curve). As we 

discussed in our July 29,2011 call and August 8, 2011 letter, there is minimal risk of oxygen 

intrusion due to the installation of final cover. Further, because the gas generation/extraction 

rate is significantly reduced, the actual volume of oxygen entering the landfill is minimal, even if 

the oxygen concentration of the gas itself is high. Therefore the risk for fire due to ambient air 

intrusion is extremely low. As discussed in the August 8, 2011 letter, sites require flexibility to 

operationally shut-off wells located in areas with declining flow and poor gas quality. 

Eliminating the requirement to conform to temperature and oxygen/nitrogen wellheads 

standards reduces regulatory burdens for both agencies and industry to process HOVs and 

alternative timelines for such exceedances. 

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2. 	 Eliminate the temperature and oxygen/nitrogen standards, and maintain the 

requirement to operate the system with negative pressure at each wellhead 

except under conditions at 60.7S3(b): 

Of the current wellhead operating standards, only pressure is directly tied to controlling 

emissions. As stated above, we do not believe that the wellhead pressure standard provides 

additional environmental protection in light of other operating incentives described above. 

However, this negative pressure parameter could be maintained to ensure a minimum standard 

of gas collection is maintained. Temperature and oxygen/nitrogen limits should be eliminated 

for the reasons stated above; primarily their regulation is counter-productive to maximizing LFG 

collection efficiency and controlling surface emissions. 

Although our priority recommendation is to remove the prescriptive wellhead standards from 

the NSPS requirements, we recognize that opinions within EPA may differ from this plausible 

and demonstrated solution. Therefore we developed the following alternative approach: 

Maintain the pressure limit and replace the temperature and oxygen/nitrogen limits with a 

methane (CH4) to carbon dioxide (C02) ratio. We believe this approach offers a more reliable 

and earlier indication of wellhead performance than current standards, as described below: 

The purpose of the temperature and oxygen/nitrogen wellhead limits is to ensure the system is 

not operated in a way that causes fires or significantly inhibits anaerobic decomposition by 

killing methanogens. The CH4/C02 ratio is a better indicator of these issues than the current 

wellhead standards because it is a direct indicator of the predominant biological process within 

the landfill. Further, most landfill owner/operators already monitor both methane and carbon 

dioxide as part of normal GCCS operations using the same field monitoring devices. 

Anaerobic methanogenic bacteria produce CH4 concentrations of approximately 55-60% by 

volume and C02 concentrations of approximately 40-45% by volume. Aerobic bacteria produce 

C02 and water - no CH4. If over-extraction occurs at a collection device, an excessive quantity 

of air enters the landfill. The oxygen from the air kills the anaerobic methanogenic bacteria and 

allows aerobic bacteria to survive, thereby reducing the concentration of CH4 and increaSing 

the concentration of C02. Therefore, CH4/C02 ratios above 1.0 (i.e., the CH4 concentration is 

greater than the C02 ratio) are considered normal and indicate that neither temperature nor 

over extraction is significantly inhibiting anaerobic decomposition or killing the methanogens 

that produce the CH4. A CH4/C02 ratio below 1.0 generally indicates a significant amount of 

aerobic decomposition is beginning to occur. Because significant aerobic decomposition usually 

preceeds a subsurface fire, the CH4/C02 ratio provides a good "early warning" indicator and 

allows the landfill owner/operator to respond before a fire begins. 

An exception is arid and older waste sites, which typically produce LFG at a much lower 

generation rate. Because of the lower LFG generation rate, it is easy for a relatively small 

volume of air to kill the methanogenic bacteria and cause the CH4/C02 ratio to fall below 1.0. 

However, in these situations the total volume of air entering the landfill is not enough to cause 

a landfill fire or significantly inhibit anaerobic decomposition. Therefore, for arid sites {i.e., 

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those with average annual precipitation less than 25" /year) or areas that contain waste in 

which all the waste in place is more than 20 years old, a CH4/C02 limit of 0.75 is more 

appropriate. 

We believe CH4/C02 ratio is a more representative parameter for measuring system 

performance and will result in far fewer variances. However, because landfill processes are 

dynamic, situations may arise where the CH4/C02 ratios would not be appropriate. Therefore, 

the rule must maintain the current process for demonstrating an alternative ratio, where 

necessary, for proper operation. 

Recommended NSPS Rule Clarifications 

If EPA retains/replaces one or more wellhead standards, we recommend EPA clarify the 

following critical issues in the Preamble and/or Final Rule changes for HOV demonstrations: 

• 	 No approval required for HOVs; rule clearly states that the owner or operator "may 

establish" such values, but somehow this has evolved to case-by-case regulatory 

approval. 

• 	 Site makes demonstration instead; dOGl:IfAentation kept on site andavailable-for review 

by air agencies. Documentation could be included in semiannual reports, if warranted. 

• 	 Demonstration designed to meet rule requirement that an alternate HOV does not 

cause/contribute to a fire, nor significantly inhibit anaerobic decomposition. 

• 	 Because of the many possible scenarios, agencies should not prescribe the types of data 

that should be collected by landfills to establish appropriate values but allow sitespecific conditions to dictate. 

If EPA retains/replaces one or more wellhead standard, then we recommend EPA clarify that 

correction action time lines that extend beyond 15 days but are less than 120 days do not 

require agency approval. Furthermore, clarification should be provided that remedies other 

than expansion of the gas well field can also be implemented in the 120-day period without 

agency approval. In the Preamble to the June 16, 1998 landfill NSPS amendments EPA stated 

IfDepending on the remedy selected to correct the problem, a different time line may be 

needed, but any timeline extending more than 120 days must be approved by the regulatory 

agency. If [F.R. Vol. 63, No. 115, P. 32748, June 16, 1998]. Industry recommends EPA finalize 

this previously proposed clarification in the rule such that: 

• 	 Corrective action timelines exceeding 15 days but less than 120 days do not require 

agency approval; agency approval is only required when additional time beyond 120 

days is necessary to correct a problem. 

• 	 Remedies other than lFG system expansion can also be implemented in the 120-day 

window without agency approval. Approval is only necessary if the remedy will take 

more tha n 120 days. 

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We also recommend that EPA clarify that sites may exclude wells located in dangerous areas 

(i.e., active filling areas, raised wells) from monitoring. This is consistent with surface emissions 

monitoring provisions (see 40 CFR 60.7S3(d)). 

Please contact us if you have any questions regarding our comments. Waste Management 

greatly values the successful collaboration we have shared with the Agency in developing 

protective and workable standards for MSW landfills. We look forward to our continued 

working relationship with you. 

Sincerely, 

Kerry Kelly, Director, 

Federal Public Affairs 

CC: F. Caponi, LACSD 

S. Crawford, SWANA 

A. Marconi, DSWA 

R. Repa, NSWMA 

R. Strube, Veolia 

P. Sullivan, SCS 

N. Wuestenberg, Republic Services 

Amy Van Kolken Banister, Senior Director, 

Corporate Air Programs 

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